Why Fence Posts Rot
The main causes of wood fence post rot are organisms, such as fungi and bacteria, that consume the wood fibers. Excess moisture creates beneficial conditions for the organisms, increasing the risk of rot. Damage from these organisms and wood-consuming insects expose more wood to risk. The portion of the post that contacts the soil and the open grain at the top and bottom ends are the most vulnerable parts of the post.
Six Ways to Protect Fence Posts from Rot
Protecting fence posts requires the right materials and the right procedures. We’ve got tips on the best ways to prevent fence post rot below, but always follow the manufacturer’s steps and safety instructions for any product you use.
1. Choose the Right Wood for Fence Posts
Protecting fence posts from rot starts with choosing the right wood:
- Pressure-treated posts and fence posts have a chemical treatment that helps prevent rot, decay and deters wood-eating insects.
- Pressure-treated fence posts need to be rated for ground contact, meaning they have additional chemical protection necessary for continuous contact with moist soil.
- Cedar and redwood posts are options since they each have natural resistance to insects and decay, but they’re typically more expensive to purchase than pressure-treated posts.
2. Treat Posts With a Wood Preservative
Wood preservatives are chemicals you can apply to posts before setting them in the ground:
- Wood preservatives add additional protection from insects, fungi and decay.
- You typically apply the preservative to fence posts with a brush or roller or by dipping each post in a bucket of the solution.
- Pay special attention to the portion of the posts that will contact the soil and to the open grain at the post ends.
3. Install Post Rot Protection Sleeves
Rot protection sleeves are an alternative to chemical wood preservatives. They create a moisture barrier around the post:
- Make sure the sleeves fit your post size.
- Install the sleeves before setting the posts in the ground.
- Some post protecters apply with a heat gun. The heat shrinks the protective barrier around the post at the ground-level point.
- Some post protectors are plastic sleeves that slide over the post ends.
4. Set the Posts Correctly
Proper installation of the fence posts helps prevent damage that can make the posts vulnerable to rot. Our wood fence how-to has step-by-step instructions for setting fence posts, but here are the key points:
- Make sure the posts are completely dry before installation. New pressure-treated posts in particular might need several weeks or a few months to dry completely.
- Dig post holes to the proper depth below the frost line.
- Add gravel to the post to allow soil around the posts to drain easily.
- Set the posts in concrete, ensuring they’re straight and plumb.
- Slope the ground away from the fence and ensure water doesn’t collect around the posts.
5. Seal the Fence Posts
Painting or staining and sealing a fence protects the posts and pickets from the moisture and ultraviolet (UV) damage that makes wood vulnerable to moisture and rot:
- Make sure the wood is completely dry before applying paint or a stain-and-sealer product.
- Prime a fence before painting or use a paint and primer in one.
- Remember, the exposed grain on the posts and picket tops and the ends of the rails need extra protection.
- Reapply stain and sealer or repaint every two to five years or as needed to keep the fence protected.
6. Maintain Your Fence Posts
Keeping your fence in top shape helps protect fence posts from damage and rot:
- Inspect the fence regularly for damage and wear.
- Reset posts that aren’t secure in the ground.
- Repair damage and tighten post-to-rail and picket-to-rail connections, as necessary.
- Check for rot and soft spots. Replace components, as necessary.
- Regularly repaint or restain and reseal the fence.
See our article on wood fence protection for more tips on maintaining your wood fence and reducing the need for repairs.
Protecting Fence Posts From Rot
Taking steps to protect your fence posts helps maintain a sturdy, good looking fence year after year. Using the right posts and applying chemicals or sleeves that protect the wood from rot are smart steps to take before you build your fence. Painting or staining and sealing the fence and inspecting it regularly helps keep it in good shape. Shop Lowes.com for the tools and materials you need for your fence project and take a look at our fencing and gate project library for more tips. You can also stop by your local Lowe’s and talk to a Red Vest associate to ensure you have everything you need for a beautiful, long-lasting fence.